a highly flexible revision control service for /etc/. It can use not only Git (the original option), but any of a long list of popular VCSes, including Mercurial, Darcs, and Bazaar. It tracks metadata changes on its own, and although you can manually enter changelogs whenever you edit a file, it also does automatic nightly checks to record any updates you've overlooked.

Etckeeper also hooks into all of the major package managers: Apt, YUM, and Pacman-G2. As a result, any changes that are triggered by pre-installation scripts, new packages, or post-installation scripts are automatically tagged in the log.